1. Field of the Invention
The present invention relates to a refrigerating apparatus.
2. Description of the Related Art
A refrigerating apparatus is known that includes two refrigerant circuits having compressors, condensers, pressure reducers, and evaporators (see, e.g., Japanese Patent Application Laid-Open Publication No. 2005-90917). Since the refrigerant discharged from the compressor in each of the two refrigerant circuits is cooled and liquefied by the condenser and evaporated by the evaporator after the depressurization by the pressure reducer, for example, an internal portion of a cold storage cabinet in thermal contact with the two evaporators in common is cooled.
This refrigerating apparatus includes a temperature sensor that detects a temperature of the internal portion, and controls the respective compressors of the two refrigerant circuits in the following manner, for example. That is, when one or both of the compressors of the two refrigerant circuits are operated, a temperature detected by the temperature sensor drops from an upper limit to a lower limit of a preset temperature range, and when both of the compressors of the two refrigerant circuits are stopped, a temperature detected by the temperature sensor increases from the lower limit to the upper limit of the preset temperature range. As above, the temperature of the internal portion is maintained within the preset temperature range by alternately performing an operation of one or two of the compressors and a stopping of the two compressors.
To accurately control the temperature in the internal portion (i.e., to maintain within a predetermined set temperature range) in the refrigerating apparatus even in a case where an internal load has been increased due to an increase in an ambient temperature, etc., it is necessary to relatively increase frequency (number of times per unit time) of periods during which both of the two compressors are in operation by, for example, operating both of the two compressors during the period of operating the compressors and shortening the period in which both of the compressors are stopped.
However, in this case, since the number of activations of the compressors is increased there are drawbacks including not only the shortening of lives of electric components such as relays but also an increase in power consumption due to activation current.
It is therefore the object of the present invention to accurately control the internal temperature while suppressing the number of activations of the compressors.